 
  

 






<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 
<html>

<!-- Mirrored from www.javapractices.com/topic/TopicAction.do?Id=122 by HTTrack Website Copier/3.x [XR&CO'2010], Sun, 12 Jun 2011 17:28:07 GMT -->
<!-- Added by HTTrack --><meta http-equiv="content-type" content="text/html;charset=UTF-8"><!-- /Added by HTTrack -->
<head>
 <title>
  Java Practices -> Buffering usually appropriate
 </title>
 <link rel="stylesheet" type="text/css" href="../stylesheet8.css" media="all">
 
 <link rel="shortcut icon" href='../images/favicon.ico' type="image/vnd.microsoft.icon">
 <meta name="description" content="Concise presentations of java programming practices, tasks, and conventions, amply illustrated with syntax highlighted code examples.">
 
 <meta name='keywords' content='java.io,java,java programming,java practices,java idiom,java style,java design patterns,java coding conventions,'>
 
 
</head>
 
<body>


<div class='menu-bar'>
 
  <a href='../home/HomeAction.html' title='Table of Contents'>Home</a> |
  <a href='../vote/VoteSummaryAction-2.html' title='View Poll Results'>Poll</a> |
   
  <A href='../feedback/FeedbackAction451f-2.html?Operation=Show' title='Send Your Feedback'>Wiki</a> |
  <b><a href='../source/SourceAction-2.html' title='Grab Source Code'>Source Code</a></b><IMG class='no-margin' SRC="../images/goldstar.gif" ALT=""> |

  <a href='http://www.web4j.com/Java_Web_Application_Framework_Overview.jsp?From=1' title='Free Download - Java Web Application Framework'><b>WEB4J</b></a> |
  
  <a href='http://www.date4j.net/' title='Replacement for java.util.Date'><b>DATE4J</b></a> |

   <a href='../references/ReferencesAction-2.html' title='References'>Links</a>
   
  <form action='http://www.javapractices.com/search/SearchAction.do' method='get' class='search-form'>
   <input type='text' name='SearchTerms' value="" size=12 maxlength=50 class='search'>
   <input type='submit' value="Search">
  </form>
 
</div>

<P>



  

 






<p class="display-messages">

 

 

</p>


<div class="main-layout">
 
   

 




<div class='page-title'>Buffering usually appropriate</div>

<div class='main-body'>
 
<br>Buffering input/output is usually recommended, and should likely be
the default style.
<p>Unbuffered input/output classes operate only on one byte at a time.
Using a buffer will often increase performance by large factors.
<p>Example runs of the following <tt>BufferDemo</tt>, with text files of
various sizes, shows gains of ~3x. (In <i>Java Platform Performance</i>
by Wilson and Kesselman, an example using a 370K JPEG file has a gain in
execution speed of 83x!)
<p>Size -&nbsp; 624 bytes :
<br><code>With buffering: 10 ms
<br>Without buffering: 30 ms</code>
<p>Size - 10,610 bytes :
<br><code>With buffering: 30 ms
<br>Without buffering: 80 ms</code>
<p>Size - 742,702 bytes :
<br><code>With buffering: 180 ms
<br>Without buffering: 741 ms</code>
<br>
<PRE>

<span class='keyword'>import</span> java.io.*;

<span class='keyword'>public</span> <span class='keyword'>final</span> <span class='keyword'>class</span> BufferDemo {

  <span class='keyword'>public</span> <span class='keyword'>static</span> <span class='keyword'>void</span> main (String... aArguments) {
    File file = <span class='keyword'>new</span> File(<span class='literal'>"C:&#092;&#092;Temp&#092;&#092;blah.txt"</span>);
    verifyFile( file );

    Stopwatch stopwatch = <span class='keyword'>new</span> Stopwatch();

    stopwatch.start();
    readWithBuffer( file );
    stopwatch.stop();
    System.out.println(<span class='literal'>"With buffering: "</span> + stopwatch);

    stopwatch.start();
    readWithoutBuffer( file );
    stopwatch.stop();
    System.out.println(<span class='literal'>"Without buffering: "</span> + stopwatch);
  }

  <span class='comment'>/**
  * @param aFile is a file which already exists and can be read.
  */</span>
  <span class='keyword'>static</span> <span class='keyword'>public</span> <span class='keyword'>void</span> readWithBuffer(File aFile) {
    <span class='keyword'>try</span> { 
      <span class='comment'>//use buffering, with default buffer size of 8K
</span>      Reader input =  <span class='keyword'>new</span> BufferedReader( <span class='keyword'>new</span> FileReader(aFile) );
      <span class='keyword'>try</span> {
        <span class='keyword'>int</span> data = <span class='literal'>0</span>;
        <span class='keyword'>while</span> ((data = input.read()) != -<span class='literal'>1</span>){
          <span class='comment'>//do nothing
</span>        }
      } 
      <span class='keyword'>finally</span> {
         input.close();
      }
    }
    <span class='keyword'>catch</span> (IOException ex){
      ex.printStackTrace();
    }
  }

  <span class='comment'>/**
  * @param aFile is an existing file which can be read.
  */</span>
  <span class='keyword'>static</span> <span class='keyword'>public</span> <span class='keyword'>void</span> readWithoutBuffer(File aFile) {
    <span class='keyword'>try</span> {
      Reader input =  <span class='keyword'>new</span> FileReader( aFile );
      <span class='keyword'>try</span> {
        <span class='comment'>//do not use buffering
</span>        <span class='keyword'>int</span> data = <span class='literal'>0</span>;
        <span class='keyword'>while</span> ((data = input.read()) != -<span class='literal'>1</span>){
          <span class='comment'>//do nothing
</span>        }
      }
      <span class='keyword'>finally</span> {
        input.close();
      }
   }
   <span class='keyword'>catch</span> (IOException ex){
     ex.printStackTrace();
   }
 }

  <span class='keyword'>private</span> <span class='keyword'>static</span> <span class='keyword'>void</span> verifyFile( File aFile ) {
    <span class='keyword'>if</span> (aFile == <span class='keyword'>null</span>) {
      <span class='keyword'>throw</span> <span class='keyword'>new</span> IllegalArgumentException(<span class='literal'>"File should not be null."</span>);
    }
    <span class='keyword'>if</span> (!aFile.exists()) {
      <span class='keyword'>throw</span> <span class='keyword'>new</span> IllegalArgumentException (<span class='literal'>"File does not exist: "</span> + aFile);
    }
    <span class='keyword'>if</span> (!aFile.isFile()) {
      <span class='keyword'>throw</span> <span class='keyword'>new</span> IllegalArgumentException(<span class='literal'>"Should not be a directory: "</span> + aFile);
    }
    <span class='keyword'>if</span> (!aFile.canWrite()) {
      <span class='keyword'>throw</span> <span class='keyword'>new</span> IllegalArgumentException(<span class='literal'>"File cannot be written: "</span> + aFile);
    }
  }
} 
</PRE>
<br>
<br>
<br>

</div>




<div class='topic-section'>See Also :</div>
<div class='main-body'>
 
  
  <a href='TopicActiondd78-2.html?Id=85'>Time execution speed</a> <br>
 
</div>


<div class='topic-section'>Would you use this technique?</div>
<div class='main-body'>
  
  <form action="http://www.javapractices.com/vote/AddVoteAction.do" method='post'>
    Yes<input type='radio' name='Choice' value='Y' >
    &nbsp;&nbsp;No<input type='radio' name='Choice' value='N'>
    &nbsp;&nbsp;Undecided<input type='radio' name='Choice' value="?" >
    &nbsp;&nbsp;<input type=submit value="Vote" >
    <input type='hidden' name='Operation' value='Apply'>
    <input type='hidden' name='TopicId' value='122'>
  </form>
</div>

<div style='height:10.0em;'></div>

 
 
</div>

  

 





<div align='center' class='legalese'>  
&copy; 2011 Hirondelle Systems |
<a href='../source/SourceAction-2.html'><b>Source Code</b></a><IMG class='no-margin' SRC="../images/goldstar.gif" ALT=""> |
<a href="mailto:webmaster@javapractices.com">Contact</a> |
<a href="http://creativecommons.org/licenses/by-nc-sa/1.0/">License</a> |
<a href='../apps/cjp.rss'>RSS</a>
<!-- ukey="2AC36CD2" -->
<!-- ckey="16DF3D87" -->
<br>

 Individual code snippets can be used under this <a href='../LICENSE.txt'>BSD license</a> - Last updated on June 6, 2010.<br>
 Over 150,000 unique IPs last month - <span title='Java Practices 2.6.5, Mon May 16 00:00:00 EDT 2011'>Built with</span> <a href='http://www.web4j.com/'>WEB4J</a>.<br>
 - In Memoriam : Bill Dirani -
</div>

<script src="../../www.google-analytics.com/urchin.js" type="text/javascript">
</script>
<script type="text/javascript">
_uacct = "UA-2633428-1";
urchinTracker();
</script>



</body>

<!-- Mirrored from www.javapractices.com/topic/TopicAction.do?Id=122 by HTTrack Website Copier/3.x [XR&CO'2010], Sun, 12 Jun 2011 17:28:07 GMT -->
<!-- Added by HTTrack --><meta http-equiv="content-type" content="text/html;charset=UTF-8"><!-- /Added by HTTrack -->
</html>
